Method of sealing tungsten and like metals in glass and seal produced by such method



May 1. ma 1,668,095

K. WEIGELT IETHOD OF SEALING TUNGSTEN AND LIKE METALS IN GLASS AND SEALPRODUCED BY SUCH METHOD Filed July 1. 1926 @www f2s INVENTOR /fHRLn/Aslz-IJ'` BY #l g 5 y ATTORNEYS 60 for instance b vli'eating't ewireand Patented May l, 1928 l 'UNITED STATES- Pari-:Nr oFFicie..V

` nim wniennr, or Naw Yoan, N. Y.

BY BUCH METHOD.

miren or me TUNGsTiiN AND Lin: mn'raiis iN amiss Nn snai. :gnonucnnApplication iiledv 'July 1,

In many types of electrical apparatus using glass, articularly when apartial vacuum is emp o ed` within the apparatus, considerablediiiYiculty has been experienced at the points where the 4lead-in wiresextend through the glass. The requirements call for an air-tightcharacter of the 'oint, so as to .prevent air from leaking into t eapparatus and impairing the vacuum, and also for keeping the lass fromcracking at the seal or adjacent creto. My resentinvention providesnovel and verye cient means for securin these desirableresults,particularly when t e part to be .sealed in the glass is a 115 wire oftungsten, molybdenum, `or metal of similar characteristics.

In ca out. my invention I coil around `the wire, rod, or other metalpart to be sealed in the glass, a rod or other elonfiu ated bodyimade ofthe glass which is to orm the seal, and then complete the article inaccordance with the conditions of the particular case. Two speciiicreferred embodiments of L m invention now be described indetail withreference to the accompanying ings, in which Fig. 1 is a: perspectivedetail view ill one of the steps in my improved method; Fig. 2 is alongitudinal s ec- 80 tion showing a furtherv step in the manufacture ofany improved article; Fig. 3 is a lo 'tudinal section through a glasssleeve in one form of my invention; Fig. 4 is a. longitudinal-sectionshowing such sleeve a plied to the intermediatefproduct illusted by Fig#25 Fig. 5' is across section on line 5-5 of Fig. 4; Fig. 6 is alongitudinal sectionthroughV a completed bodying 'in invention, as fromthe o junction 'o the parts shown iii ige. 4 aiid 5; Fig..7 isa-crosssection on-'line 7 7 of Fig. 6; Fig). 8'is alonitudinal'section, of

. the'same c aracter'as` ig."6, but showing another-'form of sea'l madeaccordingto my,

w iiiveittion,` and Fig. V9. is a cross section onf Aline9-9ofFig.8.

-denuni or other suitable Ametal is firstf vc/n a clean surfacev in anyvap ropriate m it, -while ot wi'th sodium nit Le, th wire or'inche inwa- If e operation has n this will be indicated by a unif m silveryappearance of the entire surface/of the wire.

draw-A the seal mj ,with the other parts of the apparatus. For /I.""instance,-I vmay produce separately-a 9057.9? The wire-10eonsist-ingof tungsten,mol bil i wider portion 14. 9The: portion 13'is.pref- '1 c ful,'

icas. serial No. 119,789.l

If the silvery appearance is not perfect yr uniform the purifyingoperation justescribed is re eated Y h The wire Iis then heated to atemperature 'depending on the character o'f the glass in which it is tobe imbedded or sealed. While lthe wire is. hot, I coil around ithelically plied to, that portion of they rod 11 which is` close to the'wire 10. The convolutions of the glass coil will adhere closely to eachother as well as to the wire, so that Va iable and ermanently effectiveseal will produce Itwill be understood that 'the metal and the glassemployed will be so selected that their coeiiicients of expansiomwillbear the` pro er relation to each other, being preferab y equal orapproximately so.

The glass coil 11'- whichhewire 10 has been imbedded or sealed is thenheated so that it 'will forni a tube 11"v (Eig.2) blha fusing togetherof the adjacent coils. e ceiling of the glass rod 11 on the wire 10 inthe manner, described, practicall forces out every` particle of airbetween t e wir and the coil 11', so that when such coil Ais convertedinto the tube- 11" by fusing together adjacent convolutions asdescribed, a rfect "gq joint will be obtained betweenthe wire and. lasstube 11 as ma be observed e absence of any air ubbles inthe tube,orbetween the tube and the uch air bubbleswould be detected' readily esy byhirregular refractioiis or reflections 'of` 1g t3 g l. ./Theintermediate product Fig. 2 may be connectediin `var vious ways such ,asshown in Fig. 3, comprisingv a' nar? lW.

' portion-13 into which the tube 11.. riiayl be s i erably made of glassof thai-saine' character as that used for the coil 11j if the wire'10`is a tungsten wire, the said coilwand the sleeve ortion 13 arepreferably the so glass known in the lndustry as'uo fion- 702B, whilethesleeve portion 14 is preferably made of pyrex or other suitable hardglass. In order'to obtain a good joint between the two sleeve portions13 and 14, it

is desirable that the narrow portion 13 be enlarged at the end adjoiningthe wide portion 14, so that the joint proper will be along a surfaceofgreater diameter than the narrow sleeve portion; for instance, thejoint may bein the lane indicated by a- The sleeve 13, 14 t us producedis slipped over the wire` until the glass tube 11' is within the narrowsleeve portion 13, see Figs. 4

. and 5. By the application of heat by means ing it, preferably in twodirections at right angles to -each other, as indicated at 13' and 13 inFigs. 6 and 7'. A better joint will thus be obtained. When the 702Bglassv and the tungsten wire have become cool,ithe said wirewill have auniform blood red a pearance at the portion which is embedd) sealed inthe lass. The other portion of the tungsten wire is ey or black.

According to anot er form of my invention, shown in Figs. 8 and 9, thenarrow sleeve portion 13 is dispensed with, the tube 11" (which in thiscase I prefer to make of the same lass as the relatively wide sleeve14', for instance pyrex) being connected by fusion directly withtheadjacent end of said wide sleeve 14. is produced in the same manneras described above. In this case also, that glass portion which is fusedto the sleeve may be pinched or flattened to' obtain a better joint withsaid sleeve. The sleeve 14' is connected with the tube 11" at anenlarged portion'll of 'said tube, it being noted that this enlargementis not at the very end of the tube, but the body of the tube projectsalong the wire 10 at both sides of said enlargement 11". The

joint between' the sleeve andthe tube is thus at a portion Vof enlargeddiameter at a distance fromthe ends of the tube, and this insures a goodjoint; the making of a ood` 'joint offers special diliculties when othmembersto be joined consist of hard glass Such as pyrex. 'The preferredway of making lthe'enlargement 11 consists in coiling .one or more turnsof a glass rod around a portion of the tube 11", and fusing it thereto,in the same manner that the tube 11'! 'was formed around the wire'lO.

Generally the wide sleeve portion 14, or'

the sleeve 14', is located at the outer end of the 'tube ll", that is,the end farthest away.

from the chamber in which a vacuum prevails.' Thus in Figs. 4 and 6, thenarrow sleeve Aportion 13 (which lits' close to the The tube 11" wire10) would be at the vacuum chamber. end of the/wire 10. In the widesleeve portion 14, or the sleeve 14', there is a substantial clearancebetween the wire ,10 and the surrounding glass. Of course, the glass rod11 is colled only on a portion of the wire 10, so that the latterprojects from the glass,

tube 11" at both ends thereof.

The outer or wide end of the sleeve portion 14, or the sleeve 14', issubsequently connected by fusion or in any other suitable manner withthebody 14" of theapparatus terial, which consists in coiling an elon.

gated body of vitreous material around such metal member with theconvolutions of the coil forming a continuous tubular body around saidmetal member. v

2. Thev method of sealing an elongated metal member in 'a mass ofvitreous mai terial, which consists in heating said mem'- ber and'coiling around it helically, under the application of softening heat,an elongated body of vitreous material.

3.l The method of sealing an elongated metal memberr in a mass ofvitreous material, which consists in coiling an elongated body ofvitreous material into tubular shape around a portion of said metalmember, and then connecting the coiled tubular body thus formed, with atubular member of vitreous material likewise surrounding said metalmember.`

uns1

4. The method of sealing an elongated metal member i a mass of, vitreousmaterial, which consis in coiling an elongated body of vitreous materialintotubular shape' around af portion of vsaidmetal member, inserting thearticle thus produced into a tubular member of vitreous material andconnecting such tubular member with said tubular elongated body byheating and flattening.

5. The m'ethod of an elongated metal member in a mass of vitreous ma(portion of said metal member,

serting the tubular body thus formed, into a y sleeve of vitreousmaterial and` connecting it therewith.

-6. The method of sealing 11n-elongated4 metal member in a mass ofvitreous material, which consists in coiling an elongated body ofvitreous material into tubular shape "around a portion of said metalmember, placing a wide sleeve of vitreous material around anotherportion of said metal member, out of contact therewith, but in directcontact with the tubular body formed by the coiling of said elongatedbody of vitreous material, and connecting the contacting ends of saidsleeve and coiled tubular body.

7. An elongated metal member sealed in a body of'vitreous materialcoiled around said member.

8A. An elongated metal member sealed in a body of elongatedvitreousmaterial coiled helically around said member and forming a continuoustube.

9.- A structure comprising an elongated 4metal member, a tubular sealingbody consisting of vitreous materialv coiled around a portionof saidmember, and a tubular member of vitreous material surrounding another'portion of said metal member and connected with said sealing body.

10. A structure comprising anJ elongated metal member, a tubular sealingbody consisting of vitreous material coiled around a metal member, atubular sealing body consisting of vitreous material coiled around aportion of said member, a sleeve ortion of vitreous material surroundingsaid sealing body, and another portion connected .with

said first-mentioned sleeve portion and surrounding a different portionof said metal member, out of Contact therewith.

l2. The method which consists in first connecting two tubular members ofdifferent diameters and of different kinds of vitreous material at anenlarged portion of. that member which has the smaller diameter, thenintroducing into the last-mentioned member a Wire a 'portion of which issurrounded by a sleeve of vitreous material adapted to lit into saidmember, and subsequently connecting said member with said sleeve. i

In testimony whereof I have hereunto set my hand.

KARL WEIGELT.

